To determine the prevalence of hyperprolactinemia in an ovulatory patients presenting to a general gynecology clinic, a 1-year prospective study (1978) was instituted. A total of 119 patients with at least 3 months of anovulation were screened with serum prolactin determinations. Those patients demonstrating hyperprolactinemia were further evaluated with a serum TSH level and hypocycloidal polytomography of the pituitary sella. In patients with anovulation with or without galactorrhea, a hyperprolactinemia prevalence rate of 15% was established. Anovulatory patients with galactorrhea had a hyperprolactinemia prevalence rate of 43%. This was compared to the 9% prevalence of hyperprolactinemia in patients with nongalactorrheic anovulation (P less than .001). Twenty-two percent of the patients with nongalactorrheic anovulation (2 of 9) were found to have a prolactin-secreting pituitary adenoma. In patients with hyperprolactinemia, galactorrhea, and anovulation, 67% (6 of 9) of patients had a prolactin-secreting pituitary adenoma. The authors therefore conclude that the 15% prevalence rate of hyperprolactinemia in all anovulatory women is sufficiently high to warrant continued screening of serum prolactin determinations in all anovulatory women.